--- title: Glossary slug: xdr/guide/glossary docTags: createdAt: 2026-07-30T21:09:39.144Z --- This section defines acronyms, abbreviations, and technical terms used or referenced throughout this guide. | **Term** | **Definition** | | -------------------------------------------------------- | ------------------------------------------------------------------------------------------------------------------------------------------------------------------- | | **Assigning Authority** | The organization, identified by an OID, that guarantees an identifier's uniqueness within its namespace; carried in the HL7 CX data type. | | **CA (Direct Certificate Authority)** | An authority that issues and manages Direct certificates. Surescripts is an accredited Direct CA. | | **C-CDA (Consolidated Clinical Document Architecture)** | An HL7 library of templated clinical document formats commonly exchanged through CDM. | | **CCR (Continuity of Care Record)** | A clinical document format summarizing a patient's health information; may be attached to XDR messages. | | **classCode** | An XDS metadata classification giving the high-level class of a document. | | **Clinical Direct Message** | A secure, standards-based electronic message used to exchange patient-related clinical documents between health care participants over the Surescripts network. | | **Custodian** | The party that holds and manages a subscriber's private keys; Surescripts acts as Custodian for its customers' Direct keys. | | **CX** | The HL7 data type representing an identifier together with its assigning authority, for example PATID1234^^^&1.3.6.1.4.1.99999.1\&ISO. | | **Direct Address** | An email-like address used in Direct messaging to identify senders and recipients (for example, user\@domain.direct.example.com). | | **DirectTrust** | The accreditation body and trust framework that governs Direct exchange among HISPs and maintains the policies referenced in Section 8. | | **Document Recipient** | The IHE ITI-41 role for the system that receives a Provide and Register Document Set-b transaction. | | **Document Source** | The IHE ITI-41 role for the system that initiates a Provide and Register Document Set-b transaction. | | **DSN (Delivery Status Notification)** | An asynchronous message communicating the outcome of an XDR message delivery attempt, indicating success or failure for each recipient. | | **edge system** | A customer's connecting system that sits outside the HISP boundary and exchanges messages with Surescripts on behalf of its end users. | | **HISP (Health Information Service Provider)** | An organization that provides the trust and transport services for Direct messaging. Surescripts is a DirectTrust-accredited HISP. | | **IHE (Integrating the Healthcare Enterprise)** | An initiative that promotes the coordinated use of health IT standards, including XDR. | | **ITI-41 (Provide and Register Document Set-b)** | The IHE IT Infrastructure transaction used in XDR to submit clinical documents and associated metadata. | | **limitedMetadata** | An XDS classification node indicating that a submission set or document was produced under the minimal (limited) metadata profile. | | **MDN (Message Disposition Notification)** | An email-based notification used in SMTP-based Direct messaging. For XDR-based messaging, delivery outcomes are conveyed by a DSN, not an MDN. | | **Minimal Metadata** | A reduced XDS metadata profile defined by the XDR and XDM specifications, flagged with limitedMetadata classification nodes; the default for most Direct messaging. | | **Full XDS Metadata** | The complete XDS metadata profile, used when integrating with an XDS registry or repository or when otherwise required. | | **MTOM (Message Transmission Optimization Mechanism)** | A W3C mechanism for efficiently transmitting binary content in SOAP messages; used by XDR for document attachments. | | **mTLS (Mutual Transport Layer Security)** | Two-way TLS authentication in which both client and server present and validate certificates (Section 2.5). | | **OID (Object Identifier)** | A globally unique identifier used to identify organizations, systems, and assigning authorities within HL7 and IHE standards. | | **PHI (Protected Health Information)** | Individually identifiable health information as defined under HIPAA. | | **RA (Direct Registration Authority)** | An authority that verifies the identity of organizations and individuals before certificates are issued. Surescripts is an accredited Direct RA. | | **RegistryError** | An element within a RegistryErrorList describing a single application-level error, including an errorCode. | | **RegistryResponse** | The XDR response element indicating success or failure of a Provide and Register Document Set-b transaction. | | **SOAP (Simple Object Access Protocol)** | A messaging protocol for exchanging structured information in web services, used for XDR transactions. | | **SOAP Fault** | An error generated when a SOAP request cannot be processed (for example, authentication or formatting issues). | | **XDM (Cross-Enterprise Document Media Interchange)** | An IHE specification for document exchange using media-based packaging, referenced by the XDR and XDM specification. | | **XDR (Cross-Enterprise Document Reliable Interchange)** | An IHE integration profile for secure, reliable, point-to-point exchange of clinical documents using web services. | | **XDS (Cross-Enterprise Document Sharing)** | An IHE document-sharing standard referenced for metadata handling and full XDS metadata support. |